1. Field of the Invention
This invention relates generally to ice shaving machines, and particularly to improvements in a vertically-oriented rotary ice shaving machine in which the ice block is rotated against a stationary blade by a descending drive head assembly.
2. Description of the Prior Art
Initially, the field of ice shaving machines must be distinguished from other devices for creating crushed or pulverized ice granules from blocks, irregular chunks, or cubes of ice, such as those commonly designed to make flavored "slush" drinks sold under trade names such as "Slurpee" or "Sno-Kone." Many such machines are frequently but incorrectly referred to as ice shaving machines--or their manufacturers may represent that they produce shaved ice--however the operation of those machines and the resultant product obtained are substantially dissimilar in both character and quality to true shaved ice produced using an ice shaving machine.
Conventional ice shaving machines essentially shave or scrape a thin surface layer from the planar side of a block of ice. Either the ice block or the blade is rotated, depending on the design of the machine. The shaved ice is collected in a receptacle area, and may be used for a variety of purposes including confectionery desserts to which flavored syrups, fruit, or other ingredients are added, or in the preparation of a chilled bed for the presentation of sushi, sashimi, caviar, or similar foods.
To those practiced in the associated culinary arts, both the texture and flavor of shaved ice can be readily distinguished from crushed or pulverized ice, as well as other forms of granular or flaked ice products manufactured using cutting, grinding, chopping, rapid freezing, or sublimation processes. The distinct amenability of shaved ice to certain uses makes the ability to quickly, uniformly, and safely shave ice in a restaurant or other food-preparation setting a desirable and long sought-after goal.
Those skilled in the art generally categorize ice shaving machines depending upon their vertical or horizontal orientation, with each type of machine being designed for operation in particular situations or environments. Representative examples of a variety of commercially available ice shaving machines embodying both the vertical and horizontal orientation and considered exemplary of the current state of the art are disclosed in the references submitted with this specification, as identified in the file history hereof, and which are incorporated herein by reference.
One noteworthy example of conventional ice shaving machines is shown in U.S. Pat. No. 5,402,949 to Bemer, which discloses a vertically-oriented design having a base, an intermediate table on which the ice block is rotated, a blade extending through a slot in the table, and a vertically-moveable spindle carrying an ice-engaging mechanism on the lower end. The spindle is driven by a top-mounted motor to rotate the ice block, and is threaded to travel downward exerting pressure on the ice block toward the blade.
The Bemer '949 patent also discloses such features as: a protective shield and visually open back which permit viewing the ice-shaving process from a variety of perspectives; manually raising the spindle or adjusting its height using a crank mechanism located on the side of the upper housing; and raising or lowering the blade height relative to the top surface of the table by winding a threaded adjustment mechanism through a complete continuum from a raised to a lowered position and back to the raised position.
However, the vast majority of existing ice shaving machines suffer from a variety of drawbacks, some of which are similarly presented by the Berner '949 device.
Many of the machines orient the cutting edge of the blade in an "inverted-plane" orientation, so that the angled face of the blade is disposed toward the surface of the ice block being shaved. Such an orientation is shown in FIG. 4 of Bemer '949 patent, however the actual angle of the face of the blade forming the cutting edge is more closely parallel to the surface of the ice block than depicted in the diagram. As a result, the block of ice tends to ride on the angled face of the blade, and the sharp edge of the blade "scrapes" obliquely against the ice rather than actually "chiseling" into the lower surface of the ice block. The block of ice will bounce along the angled face of the blade if the surface is not uniform, and the results are poor quality and slow production.
Since the inner radial edge of the blade extends entirely inward to the axial center of the ice block, the shaving process adjacent the center of rotation is retarded. Essentially, the inner radial edge of the blade acts as a bearing supporting the block, forcing the ice near the center to melt or crack away in order to allow shaving along the rest of the blade's length. This leads to misalignment and therefore non-uniform contact between the blade and ice block. As a result, only the outer segment of the blade may contact the ice surface sufficiently to shave the block--thus escalating the misalignment problem--and the downwardly protruding ice near the center can cause the ice block to wobble relative to the blade. These deficiencies slow the shaving process significantly, and seriously denigrate the quality of the resultant product. In addition, some systems require tempering the ice block at ambient room temperature for periods up to half an hour prior to initiating shaving, as well as monitoring and adjusting the blade's height throughout a transitional period when starting to shave a new ice block (and sometimes continuously throughout shaving the entire ice block).
The ice-engaging mechanism must usually be spiked into the top surface to provide a good purchase, which can shatter an otherwise stable block of ice. Spiking can also erode or damage the top surface of the block, resulting in uneven downward pressure and non-uniform shaving. A block can also be fractured (without visible or noteworthy damage) during spiking, only to subsequently break apart or explode once the motor is engaged or the shaving process reaches a critical fissure. In such cases, the block must be replaced, and damage to the machine or injury to the operator can occur.
Because lowering the sharp edge of the blade to a protected or retracted position beneath the upper surface of the table requires operating the manual height adjustment mechanism--which is both time consuming and nullifies any prior optimized height adjustments--operators of many machines fail to lower the blades sufficiently (or at all) when changing blocks of ice. The presence and accessibility of the exposed blade results in many serious accidents, particularly because fluid adhesion between the remnant of an ice block and the tables' smooth surface requires significant force to overcome, with the remnant (and operator's fingers) sliding suddenly across the surface of the table when lateral force is applied to dislodge the remnant.
Some vertically-oriented ice shaving machines have completely exposed operating mechanisms, without protective guards or shields surrounding the drive head assembly, ice block, or upper surface of the table. Of the designs which do incorporate some physical barriers to protect the operator when the machine is running, mechanical safety interlocks linking closure of the safety guards to raising the blade or operating the drive of lift motors have not appeared in the marketplace. Only the most basic forms of electrical interrupts or kill switches have been utilized in the industry.
Vertical ice shaving machines in which the spindle descends relative to the table during the shaving process also present an exposed end of the rotating spindle above the drive head assembly. The spindle either protrudes perpendicularly a significant distance above the housing when the drive shaft is raised--resulting in noncompliance with local safety regulations and certification standards applicable to other types of industrial or commercial equipment--or requires an extremely large or inefficiently-shaped upper housing be retrofitted to enclose the spindle. Positioning the motor, a differential, and other components at the top of the machine (well above a rapidly spinning block of ice) makes the machines top-heavy and very unstable. In addition, the center of mass of the ice block is very seldom perfectly aligned with the axis of rotation--and may even shift significantly during shaving due to variations in the shape or density of the ice block--creating an unbalanced centrifugal force which further destabilizes the machine when the ice block is spun rapidly.
Consequently, the devices require a wider footprint and heavier base than would otherwise be necessary, utilize a shorter available stroke length to preserve stability, are difficult or dangerous to place in confined areas or along traffic patterns, are inconvenient to service, and will more readily permit moisture or other contamination to reach the spindle and interior of the drive head assembly through the open housing.
Moreover, these machines pose special obstacles to use in a commercial food preparation environment, such as the risk of injury to operators from the exposed spindle, and the need to enclose or isolate the moving mechanisms to prevent lubricants, dirt, or debris from being ejected onto dishware, utensils, or foodstuffs.
As such, the current commercially-available array of vertical ice shaving machines pose significant and unjustified risks to the operators' health and safety. These machines do not meet basic international safety requirements, and have not obtained conventional certification from the applicable regulatory and industry-approval bodies such as Underwriter's Laboratories (UL) without variation or divergence from their normal and meaningful safety and injury-prevention standards.